From what I've seen on this line, I don't think Veronica's last name was Medici, or Cremona. I think Medici slipped in through a name mix-up, and Cremona was the name of the town she was from. I believe her last name was Boncompagni.
If the name Veronica was unusual for the time, then it is highly coincidental that 2 Veronicas would be born in Venice about the same time (1583 & 1584), both be born into noble families, AND die at the same age. And this woman's also referred to as "Donna Veronica." (But then her tree is full of people referred to as "Don" and "Donna" so, anyway. . . .
Although Veronica Boncompagni is shown as a nun, this was a different time from today. Madelein/Madalena Máxima de Miranda (1690-?), mother of Gaspar de Braganza (1716-1789) was also a nun. Gaspar later became the archbishop of Braga.
Pietro's connection to the Catholic Church would have to be actually documented to be real, and I haven't found any yet. But the political and religious offices that are found on Veronica's tree would seem to make it hard not to be, especially when his father was the ducal secretary.
I've found 4 copies of her tree, but here's 1. genealogy.euweb.cz/italy/boncomp1.html